When creating Message objects from scratch, you often
need to encode the payloads for transport through compliant mail servers. This
is especially true for image/* and text/* type messages
containing binary data.

The email package provides some convenient encodings in its
encoders module. These encoders are actually used by the
MIMEAudio and MIMEImage
class constructors to provide default encodings. All encoder functions take
exactly one argument, the message object to encode. They usually extract the
payload, encode it, and reset the payload to this newly encoded value. They
should also set the Content-Transfer-Encoding header as appropriate.

Note that these functions are not meaningful for a multipart message. They
must be applied to individual subparts instead, and will raise a
TypeError if passed a message whose type is multipart.

Encodes the payload into quoted-printable form and sets the
Content-Transfer-Encoding header to quoted-printable[1].
This is a good encoding to use when most of your payload is normal printable
data, but contains a few unprintable characters.

Encodes the payload into base64 form and sets the
Content-Transfer-Encoding header to base64. This is a good
encoding to use when most of your payload is unprintable data since it is a more
compact form than quoted-printable. The drawback of base64 encoding is that it
renders the text non-human readable.